CN111731896B

CN111731896B - Sheet conveying apparatus and image forming system

Info

Publication number: CN111731896B
Application number: CN201911142175.5A
Authority: CN
Inventors: 丸山真司; 山本干夫; 曾我直史
Original assignee: Toshiba TEC Corp
Current assignee: Toshiba TEC Corp
Priority date: 2019-03-25
Filing date: 2019-11-20
Publication date: 2023-10-24
Anticipated expiration: 2039-11-20
Also published as: EP3715292B1; US20210395030A1; EP3715292A1; US20200307934A1; US11820623B2; CN111731896A

Abstract

The present invention relates to a sheet conveying apparatus and an image forming system. The sheet conveying device of the embodiment has a positioning mechanism and a conveying width variable mechanism. The aligning mechanism collates the positions of the leading ends of the sheets conveyed along the conveying path by touching the sheets against the nip portion. A conveying width variable mechanism is provided at a position upstream of the nip portion in a conveying direction of the sheet. The conveying width variable mechanism makes the width of the conveying path near the clamping part when the sheet touches the clamping part larger than the width of the conveying path near the clamping part when the sheet passes through the clamping part after touching the clamping part.

Description

Sheet conveying apparatus and image forming system

Technical Field

Embodiments of the present invention relate to a sheet conveying apparatus and an image forming system.

Background

An image forming system (e.g., MFP) includes a sheet conveying device that conveys a sheet along a conveying path. The sheet conveying apparatus includes a positioning mechanism that performs a positioning process of correcting an inclination of a sheet conveyed along a conveying path. For example, the alignment process is performed by bringing the sheet into contact with the nip portion of a pair of stopped rollers to flex the sheet. However, if the amount of inclination (skew) of the sheet is excessively large at the time of performing the alignment treatment, the sheet may be inclined to fluctuate at the time of bending the sheet. If the sheet is conveyed by a pair of rollers in a state in which the sheet is obliquely undulated, sheet damage such as wrinkles and creases may occur on the sheet.

Disclosure of Invention

The sheet conveying device of the embodiment has a positioning mechanism and a conveying width variable mechanism. The aligning mechanism collates the positions of the leading ends of the sheets conveyed along the conveying path by touching the sheets against the nip portion. The conveying width variable mechanism is provided at a position upstream of the nip portion in a conveying direction of the sheet. The conveying width variable mechanism makes the width of the conveying path near the clamping part when the sheet touches the clamping part larger than the width of the conveying path near the clamping part when the sheet passes through the clamping part after touching the clamping part.

An image forming system according to another embodiment forms an image on a sheet, and includes the sheet conveying apparatus.

Drawings

Fig. 1 is a front view showing an example of an image forming system according to an embodiment.

Fig. 2 is a schematic diagram showing a main portion of the sheet conveying apparatus of the embodiment.

Fig. 3 is a view of a main portion of the sheet conveying apparatus of the embodiment (a view of an arrow III in fig. 2) as seen from a side in the second conveying orthogonal direction.

Fig. 4 is an explanatory diagram of deflection of the sheet when the sheet is conveyed straight in the comparative example. Fig. 4 (a) is a view before the sheet enters the nip. Fig. 4 (b) is a view showing a state in which the sheet is deflected by touching the nip portion.

Fig. 5 is an explanatory view of deflection of the sheet when the sheet is obliquely conveyed in the comparative example. Fig. 5 (a) is a view before the sheet enters the nip. Fig. 5 (b) is a view showing a state in which the sheet is deflected by touching the nip portion.

Fig. 6 is an explanatory diagram of the alignment operation of the sheet according to the embodiment.

Fig. 7 is an explanatory diagram of a conveying operation of the sheet according to the embodiment.

Fig. 8 is a schematic diagram showing a main portion of a sheet conveying apparatus according to a modification of the embodiment.

Detailed Description

Next, a sheet conveying apparatus and an image forming system according to embodiments will be described with reference to the drawings. In the drawings, the same reference numerals are given to the same structures. In the drawings, the size and shape of each component are exaggerated or simplified for the convenience of observation.

Fig. 1 is a front view showing an example of an image forming system 1 according to the embodiment. As shown in fig. 1, the image forming system 1 includes an image forming apparatus 2 and a post-processing apparatus 3. The image forming apparatus 2 forms an image on a sheet-like medium (hereinafter referred to as a "sheet") such as paper. The post-processing device 3 performs post-processing on the sheet conveyed from the image forming device 2. The post-processing device 3 is an example of a "sheet processing device".

The image forming apparatus 2 includes a control panel 11, a scanner unit 12, a printer unit 13, a paper feed unit 14, a paper discharge unit 15, and an image forming control unit 16.

The control panel 11 includes various keys for receiving operations of a user. For example, the control panel 11 receives an input concerning the type of post-processing of the sheet. The control panel 11 transmits information on the type of post-processing input to the post-processing device 3.

The scanner 12 includes a reader for reading image information of the copy target. The scanner section 12 transfers the read image information to the printer section 13.

The printing section 13 forms an output image (hereinafter referred to as "toner image") with a developer such as toner based on image information sent from the scanning section 12 or an external device. The printing section 13 transfers the toner image onto the surface of the sheet. The printing section 13 applies pressure to the toner image transferred to the sheet while heating the toner image, thereby fixing the toner image to the sheet.

The paper feed unit 14 feeds the sheets to the printing unit 13 one by one in accordance with timing of forming the toner image by the printing unit 13.

The paper discharge portion 15 conveys the sheet discharged from the printing portion 13 to the post-processing apparatus 3.

The image forming control section 16 controls the overall operation of the image forming apparatus 2. That is, the image forming control section 16 controls the control panel 11, the scanner section 12, the printer section 13, the paper feed section 14, and the paper discharge section 15. The image forming control section 16 is formed of a control circuit including a CPU, a ROM, and a RAM.

Next, the post-processing device 3 will be described.

The post-processing device 3 is disposed adjacent to the image forming device 2. The post-processing device 3 performs post-processing designated by the control panel 11 on the sheet conveyed from the image forming device 2. For example, the post-processing is a stapling processing or a sorting processing. The post-processing device 3 includes a standby unit 21, a processing unit 22, a discharge unit 23, and a post-processing control unit 24. In the embodiment, the sheet is conveyed from the image forming apparatus 2 to the discharge portion 23.

The standby portion 21 temporarily retains (buffers) the sheet conveyed from the image forming apparatus 2. For example, the standby unit 21 causes the processing unit 22 to standby a plurality of subsequent sheets while performing post-processing on the preceding sheet. The standby unit 21 is disposed above the processing unit 22. When the post-processing of the preceding sheet in the processing unit 22 is completed, the standby unit 21 drops the retained sheet toward the processing unit 22.

The processing unit 22 performs post-processing on the sheet. For example, the processing unit 22 pairs Ji Duo sheets. The processing section 22 performs binding processing on the aligned sheets. Thereby, a plurality of sheets are stapled together. The processing unit 22 discharges the sheet subjected to the post-processing to the discharge unit 23.

The discharge unit 23 includes a fixed tray 23a and a movable tray 23b. The fixed tray 23a is provided at the upper portion of the post-processing device 3. The movable tray 23b is provided on the side of the post-processing device 3. The sheets after the sorting process are discharged to the fixed tray 23a and the movable tray 23b.

The post-processing control unit 24 controls the overall operation of the post-processing device 3. That is, the post-processing control unit 24 controls the standby unit 21, the processing unit 22, and the discharge unit 23. The post-processing control section 24 is formed of a control circuit including a CPU, a ROM, and a RAM.

For example, the post-processing control section 24 switches between a control processing mode and a non-processing mode (normal mode). Here, the processing mode refers to a mode in which post-processing is performed on a sheet. For example, the processing mode includes a sorting mode and a binding mode. The non-processing mode is a mode in which the sheet is directly conveyed without post-processing the sheet.

The control panel 11 includes a mode selection unit (operation unit, not shown) capable of selecting a processing mode and a non-processing mode. For example, the mode selecting unit is a button provided on the control panel 11. The user selects the "processing mode" and presses a button at the time of mode selection, thereby causing the post-processing control section 24 to post-process the sheet. On the other hand, when the user selects the "non-processing mode" and presses a button at the time of mode selection, the post-processing control unit 24 directly discharges the sheet without post-processing the sheet.

Next, a sheet conveying apparatus will be described.

The image forming system 1 includes a sheet conveying apparatus 30 (see fig. 2). In the embodiment, the sheet conveying device 30 is provided to the image forming apparatus 2. The sheet conveying apparatus 30 is disposed between the paper feed section 14 and the printing section 13. The sheet conveying apparatus 30 corrects the inclination of the sheet conveyed from the paper feed portion 14 toward the printing portion 13.

Fig. 2 is a schematic diagram showing a main portion of the sheet conveying apparatus 30 of the embodiment. Fig. 2 shows a state in which the tip end portion of the guide 51 abuts against the second regulating projection 57. As shown in fig. 2, a conveyance path 31 is provided inside the image forming apparatus 2 (see fig. 1). The sheet conveying apparatus 30 includes a registration mechanism 40, a conveying width variable mechanism 50, and a conveying mechanism 60.

First, the conveyance path 31 will be described.

The conveying path 31 is provided along a vertical plane. The sheet is conveyed from below to above along the conveying path 31. The sheet is conveyed from the paper feed portion 14 (e.g., paper feed cassette 32) to the printing portion 13 (e.g., image forming portion) via the sheet conveying apparatus 30. Hereinafter, in the sheet conveying direction Vs (hereinafter referred to as "sheet conveying direction Vs"), the paper feed portion 14 side (lower side of the paper surface in fig. 2) is referred to as "upstream side". In the sheet conveying direction Vs, the printing section 13 side (upper side of the drawing sheet of fig. 2) is set to the downstream side.

Hereinafter, a direction V1 (a paper depth direction of fig. 2) orthogonal to the sheet conveying direction Vs in the sheet surface of the sheet conveyed along the conveying path 31 is referred to as a "first conveying orthogonal direction V1". Hereinafter, a direction V2 (a left-right direction of the drawing sheet of fig. 2) orthogonal to the sheet conveying direction Vs and the first conveying orthogonal direction V1, respectively, is referred to as a "second conveying orthogonal direction V2".

In fig. 2, reference numeral 32 denotes a paper feed cassette, reference numeral 33 denotes a pickup roller, reference numeral 34 denotes an intermediate transfer belt, reference numeral 35 denotes a backup roller, reference numeral 36 denotes a tension roller, and reference numeral 37 denotes a secondary transfer roller.

The sheet feed cassette 32 accommodates the sheet S.

The pickup roller 33 takes out the sheet S from the sheet feed cassette 32.

The intermediate transfer belt 34, the backup roller 35, the tension roller 36, and the secondary transfer roller 37 constitute the printing section 13.

The support roller 35 supports the intermediate transfer belt 34.

The secondary transfer roller 37 is opposed to the backup roller 35 with the intermediate transfer belt 34 interposed therebetween.

Next, the conveying mechanism 60 will be described.

The conveying mechanism 60 is provided at a position upstream of the registration mechanism 40 in the sheet conveying direction Vs. The conveying mechanism 60 includes conveying roller pairs 61 and 62 and a motor 63 for conveying the sheet.

The conveying roller pairs 61, 62 are disposed near the pickup roller 33. The pair of conveying rollers 61, 62 includes a first conveying roller 61 and a second conveying roller 62 that face each other. The first conveying roller 61 is driven by a motor 63 for sheet conveyance. The second conveying roller 62 rotates (driven rotation) with the rotation of the first conveying roller 61. The pair of conveying rollers 61, 62 conveys the sheet fed from the pickup roller 33 toward the downstream side of the conveying path 31. The conveying rollers 61 and 62 convey the sheet by abutting the sheet when passing the sheet through the nip portion 44 of the registration roller pair 41 and 42. When the sheet is brought into contact with the nip portion 44, the conveying rollers 61 and 62 convey the sheet by abutting the sheet.

In fig. 2, reference numeral 70 denotes a conveyance guide wall, reference numeral 71 denotes a linear guide wall, and reference numeral 72 denotes a curved guide wall.

The conveyance guide wall 70 forms the conveyance path 31 between the pickup roller 33 and the conveyance roller pair 61, 62.

The linear guide wall 71 forms the conveying path 31 between the conveying roller pairs 61 and 62 and the registration roller pairs 41 and 42. The linear guide wall 71 extends linearly along the sheet conveying direction Vs.

The curved guide wall 72 forms the conveying path 31 with the linear conveying guide wall 70. The curved guide wall 72 forms a sheet deflection space 73 at a position close to the conveying roller pair 61, 62. The curved guide wall 72 is convexly curved in a direction away from the linear guide wall 71.

Fig. 3 is a view of a main portion of the sheet conveying apparatus 30 of the embodiment (a view of an arrow III in fig. 2) as seen from a side of the second conveying orthogonal direction V2. In fig. 3, illustration of the conveyance guide walls 70 and the like is omitted.

As shown in fig. 3, the first conveying roller 61 is fixed to a first conveying shaft 65 (rotation shaft). The first conveying rollers 61 are arranged at intervals along the first conveying shaft 65. The two first conveying rollers 61 are disposed with the first conveying orthogonal direction center line C1 interposed therebetween. The first conveying shaft 65 extends in a straight line in the first conveying orthogonal direction V1. The first conveying shaft 65 is longer than the sheet S in the first conveying orthogonal direction V1. Both ends of the first conveying shaft 65 are rotatably supported by an image forming apparatus main body via bearings, not shown. The first conveying shaft 65 is connected to the sheet conveying motor 63. The sheet conveying motor 63 rotationally drives the first conveying shaft 65.

As shown in fig. 2, the second conveying roller 62 is fixed to a second conveying shaft 66 (rotation shaft) extending parallel to the first conveying shaft 65. The second conveying roller 62 is disposed opposite to the first conveying roller 61. Both ends of the second conveying shaft 66 are rotatably supported by an image forming apparatus main body via bearings, not shown.

In fig. 3, reference numeral L1 denotes a length of the sheet in the sheet conveying direction Vs, and reference numeral L2 denotes a sheet conveying path length. Here, the sheet conveying path length L2 refers to a distance between the central axis of the first conveying roller 61 and the central axis of the first registration roller 41 in the sheet conveying direction Vs. The sheet conveying path length L2 is shorter than the length L1 of the sheet (L2 < L1).

Next, the alignment mechanism 40 will be described.

As shown in fig. 2, the alignment mechanism 40 includes alignment roller pairs 41 and 42 and an alignment motor 43.

The registration roller pairs 41, 42 are provided between the conveying roller pairs 61, 62 and the secondary transfer roller 37 (support roller 35) in the sheet conveying direction Vs. The registration roller pairs 41 and 42 include first registration rollers 41 and second registration rollers 42 that face each other. The first registration roller 41 and the second registration roller 42 are abutted against each other to form a nip 44. The alignment mechanism 40 collates the positions of the leading ends of the sheets by touching the sheets conveyed along the conveying path 31 to the nip 44. Here, the position of the leading end of the sheet refers to a position of the downstream end of the sheet in the sheet conveying direction Vs.

The first registration roller 41 is a driving roller driven by a motor 43 for registration. The first registration roller 41 rotates forward when the sheet passes through the nip 44. When the sheet passes through the nip 44, the first registration roller 41 rotates clockwise (in the direction of arrow R1 in fig. 7) (rotates in the forward direction). The first registration roller 41 rotates reversely when the sheet contacts the nip 44. When the sheet contacts the nip 44, the first registration roller 41 rotates counterclockwise (in the direction of arrow R2 in fig. 6) (reverse rotation).

The second registration roller 42 is a driven roller that rotates (driven rotation) with the rotation of the first registration roller 41. The registration roller pairs 41 and 42 convey the sheet fed from the conveying roller pairs 61 and 62 toward the downstream side of the conveying path 31.

As shown in fig. 3, the first registration roller 41 is fixed to a first registration shaft 45 (rotation shaft). The first registration rollers 41 extend along a first registration axis 45. The first registration roller 41 has a shape that is axisymmetric with respect to the first conveyance orthogonal direction center line C1 as a symmetry axis. The first pair of positioning shafts 45 extend in a straight line in the first conveyance orthogonal direction V1. The first registration roller 41 is longer than the sheet in the first conveyance orthogonal direction V1. The first registration shaft 45 is longer than the first registration roller 41 in the first conveyance orthogonal direction V1. Both ends of the first registration shaft 45 are rotatably supported by an image forming apparatus main body via bearings, not shown. The first alignment shaft 45 is connected to the alignment motor 43. The alignment motor 43 rotationally drives the first alignment shaft 45.

As shown in fig. 2, the second registration roller 42 is fixed to a second registration shaft 46 (rotation shaft) extending parallel to the first registration shaft 45. The second registration roller 42 is disposed opposite to the first registration roller 41. Both ends of the second registration shaft 46 are rotatably supported by an image forming apparatus main body via bearings, not shown.

Next, the conveyance width variable mechanism 50 will be described.

The conveying width variable mechanism 50 is provided at a position upstream of the nip 44 in the sheet conveying direction Vs. Hereinafter, the width of the conveying path 31 near the nip 44 is referred to as "conveying width near the nip". In fig. 2, a conveying width near the nip is denoted by reference numeral D1.

Here, a virtual straight line (lead line) passing through the pair of conveying rollers 61, 62 and the pair of registration rollers 41, 42 is set. The conveying width near the nip portion is the width of the conveying path 31 near the nip portion 44 in the second conveying orthogonal direction V2, and is the interval between the virtual straight line and the leading end of the guide 51. Here, the leading end of the guide 51 refers to an upstream end of the guide 51 in the sheet conveying direction Vs. The conveying width variable mechanism 50 makes the conveying width near the nip portion when the sheet touches the nip portion 44 larger than the conveying width near the nip portion when the sheet passes through the nip portion 44 after the sheet touches the nip portion 44.

The conveyance width variable mechanism 50 includes a guide 51, position regulating portions 52 and 53, and torque transmission cutting portions 54 and 55 (see fig. 3).

The guide 51 operates in association with the rotation of the first registration roller 41 as a driving roller. The guide 51 swings about the first alignment shaft 45. The guide 51 swings coaxially with the first registration roller 41. The swing center of the guide 51 is coaxial with the rotation center of the first registration roller 41. The guide 51 makes the conveying width near the nip portion when the first registration roller 41 rotates reversely larger than the conveying width near the nip portion when the first registration roller 41 rotates forwardly.

As shown in fig. 3, the guide 51 is longer than the sheet S in the first conveyance orthogonal direction V1. The length W2 of the guide 51 in the first conveyance orthogonal direction V1 is longer than the width W1 of the sheet in the first conveyance orthogonal direction V1 (W2 > W1). The guide 51 includes a guide body 51a, a reinforcing rib 51b, and a connecting piece 51c. The guide body 51a, the reinforcing rib 51b, and the connecting piece 51c are integrally formed of the same member.

The guide main body 51a has a plate shape extending in the first conveyance orthogonal direction V1. The guide main body 51a extends outward (radially outward of the first registration roller 41) from the first registration shaft 45 as viewed in the first conveyance orthogonal direction V1 (see fig. 2). Thereafter, the guide body 51a is bent and extends so as to be farther radially outward from the conveying path 31.

As shown in fig. 2, the reinforcing rib 51b protrudes from the bent portion of the guide body 51a to the opposite side of the conveying path 31. As shown in fig. 3, the reinforcing rib 51b extends in a straight line in the first conveyance orthogonal direction V1 throughout the entire guide body 51 a.

The connecting pieces 51c are provided at the respective ends of the guide body 51 a. The connecting pieces 51c connect the respective ends of the guide body 51a and the respective ends of the first pair of positioning shafts 45, respectively.

The position regulating portions 52, 53 include a first stopper 52 and a second stopper 53.

The first stopper 52 can abut against the first end of the guide 51 in the first conveyance orthogonal direction V1. The second stopper 53 can abut against the second end of the guide 51 in the first conveyance orthogonal direction V1. Here, the second end of the guide 51 refers to an end on the opposite side of the first end of the guide 51 in the first conveyance orthogonal direction V1. Each stopper 52, 53 is fixed to the image forming apparatus main body.

Each stopper 52, 53 includes a first restricting protrusion 56, a second restricting protrusion 57, and a connecting portion 58.

As shown in fig. 2, the first restricting protrusion 56 and the second restricting protrusion 57 are disposed at a distance from each other in the second conveyance orthogonal direction V2. The connecting portion 58 connects the first restricting protrusion 56 and the second restricting protrusion 57. The connecting portion 58 extends in the second conveyance orthogonal direction V2. The coupling portion 58 is disposed outside the guide 51 in the first conveyance orthogonal direction V1 (see fig. 3).

The first regulating projection 56 can abut against a surface F1 (hereinafter referred to as a "first surface F1") on the conveying path 31 side of the distal end portion of the guide 51. The first regulating projection 56 sets the end of the first registration roller 41 in the swinging direction of the guide 51 at the time of normal rotation (see fig. 7). The first regulating projection 56 regulates the movement of the guide 51 when the first registration roller 41 rotates forward so that the sheet can pass through the nip portion 44. When the leading end portion of the guide 51 abuts against the first regulating projection 56, the first surface F1 is linear, and the linear extends so as to approach the linear guide wall 71 as the downstream side in the sheet conveying direction Vs is closer (see fig. 7).

The second regulating projection 57 can abut against a surface F2 (hereinafter referred to as a "second surface F2") of the distal end portion of the guide 51 on the opposite side to the conveying path 31. The second regulating projection 57 sets the end of the first registration roller 41 in the swinging direction of the guide 51 at the time of the reverse rotation. The second regulating projection 57 regulates the movement of the guide 51 when the first registration roller 41 rotates reversely so that a deflection space 74 of the sheet can be formed at a position near the nip 44. When the leading end portion of the guide 51 abuts against the second regulating projection 57, the second surface F2 is linear, and the linear extends so as to be farther from the linear guide wall 71 toward the downstream side in the sheet conveying direction Vs.

The torque transmission cut-off portions 54 and 55 (see fig. 3) interrupt the connection between the guide 51 and the first pair of positioning shafts 45 before an overload is applied to the guide 51, and cut off the torque transmission. When the first registration roller 41 rotates in the forward direction, the torque transmission cutting portions 54 and 55 cut off the torque transmission when the tip end portion of the guide 51 abuts against the first regulating projection 56. Thereby, the torque transmission cut-off portions 54 and 55 maintain the abutting state of the tip portion of the guide 51 and the first restricting convex portion 56 without applying an overload to the guide 51. When the first registration roller 41 rotates in the reverse direction, the torque transmission cutting portions 54 and 55 cut off the torque transmission when the tip end portion of the guide 51 abuts against the second regulating projection 57. Thereby, the torque transmission cut-off portions 54 and 55 maintain the abutting state of the distal end portion of the guide 51 and the second restricting convex portion 57 without applying an overload to the guide 51.

As shown in fig. 3, the torque transmission cutoff portions 54 and 55 include a first torque limiter 54 and a second torque limiter 55. The first torque limiter 54 is provided at a first end of the first alignment shaft 45 extending in the first conveyance orthogonal direction V1. The second torque limiter 55 is provided at a second end of the first pair of positioning shafts 45. Here, the second end of the first pair of positioning shafts 45 refers to an end on the opposite side of the first end of the first pair of positioning shafts 45. Each torque limiter 54, 55 is provided between each connecting piece 51c of the guide 51 and each end of the first pair of positioning shafts 45.

Next, deflection of the sheet when the sheet alignment process is performed will be described. The following description is a description of a comparative example without the conveyance width variable mechanism 50 of the embodiment.

As shown in fig. 4 (a), when the sheet S is conveyed straight, the width direction center line Cs of the sheet S coincides with the first conveyance orthogonal direction center line C1.

As shown in fig. 4 b, when the sheet S is conveyed straight, the undulation direction of the sheet S is parallel to the extending direction (first conveyance orthogonal direction V1) of the registration roller pairs 41, 42. Therefore, even if the sheet S enters the nip 44 while being kept in a wavy state, sheet damage such as wrinkles and creases will not occur on the sheet S.

As shown in fig. 5 (a), when the sheet S is obliquely conveyed, the width direction center line Cs of the sheet S intersects with the first conveyance orthogonal direction center line C1.

As shown in fig. 5 b, when the sheet S is obliquely conveyed, the undulation direction of the sheet S intersects the extending direction (first conveying orthogonal direction V1) of the registration roller pairs 41, 42. Therefore, if the sheet S enters the nip portion 44 while being undulated, sheet damage such as wrinkles and creases is likely to occur in the sheet S.

Next, an example of the alignment operation of the sheet according to the embodiment will be described.

Fig. 6 is an explanatory diagram of the alignment operation of the sheet according to the embodiment. In fig. 6, the position regulating portions 52 and 53 are not shown.

As shown in fig. 6, when the first registration roller 41 rotates reversely (in the direction of arrow R2), the guide 51 swings away from the linear guide wall 71 in conjunction with the reverse rotation of the first registration roller 41. Then, the second surface F2 of the distal end portion of the guide 51 abuts against the second restricting protrusion 57 (see fig. 2). Thereby, a deflection space 74 of the sheet S is formed between the first surface F1 of the leading end portion of the guide 51 and the linear guide wall 71. That is, in the vicinity of the nip portion 44, a deflection space 74 of the sheet S sufficient for inclination correction of the sheet S is ensured. The guide 51 makes the conveying width near the nip portion when the first registration roller 41 rotates reversely larger than the conveying width near the nip portion when the first registration roller 41 rotates forwardly.

If the first conveying roller 61 rotates in the forward direction, the sheet S contacts the nip 44. When the sheet S touches the nip 44, the sheet S flexes along the first surface F1 of the leading end portion of the guide 51. Thereafter, the sheet S is deflected in the space 73 between the linear guide wall 71 and the curved guide wall 72. Next, the deflection shape of the sheet S in fig. 6 will be described. The sheet S extends further from the nip 44 toward the downstream side in the sheet conveying direction Vs than the linear guide wall 71 as viewed in the first conveying orthogonal direction V1. Thereafter, the sheet S extends downward through the downstream end of the curved guide wall 72. Thereafter, the sheet S extends to reach the nip 64 of the conveying roller pair 61, 62 so as to approach the forming portion of the conveying path 31 as the downstream side in the sheet conveying direction Vs is separated from the curved guide wall 72.

In this way, the second surface F2 of the leading end portion of the guide 51 abuts against the second regulating projection 57 (see fig. 2), and a deflection space 74 of the sheet S sufficient for inclination correction of the sheet S is secured in the vicinity of the nip portion 44. Therefore, even in the case of obliquely conveying the sheet S, the inclination of the sheet S can be sufficiently corrected.

Next, an example of the conveying operation of the sheet according to the embodiment will be described.

Fig. 7 is an explanatory diagram of a conveying operation of the sheet according to the embodiment. In fig. 7, the position regulating portions 52 and 53 are not shown.

As shown in fig. 7, after the sheet S is aligned, the first alignment roller 41 rotates forward (rotates in the direction of arrow R1). When the first registration roller 41 rotates in the forward direction, the guide 51 swings in a direction approaching the linear guide wall 71 in conjunction with the forward rotation of the first registration roller 41. Then, the first surface F1 of the distal end portion of the guide 51 abuts against the first restricting convex portion 56 (see fig. 2). Thereby, a space 75 through which the sheet S can pass is formed between the first surface F1 of the leading end portion of the guide 51 and the linear guide wall 71, and a deflection space of the sheet S is not formed. That is, in the vicinity of the nip portion 44, a deflection space 74 (see fig. 6) of the sheet S sufficient for inclination correction of the sheet S is not secured.

The first conveying roller 61 maintains the forward rotation when the conveying operation of the sheet S is performed. When the first conveying roller 61 rotates in the forward direction and the first registration roller 41 rotates in the forward direction, the sheet S passes through the nip 44. When the sheet S passes through the nip 44, the sheet flexes in the space 73 on the downstream side of the leading end of the guide 51. That is, the sheet S flexes in the space 73 between the linear guide wall 71 and the curved guide wall 72. Next, the deflection shape of the sheet S in fig. 7 will be described. The sheet S extends linearly from the nip 44 along the first surface F1 as viewed in the first conveyance orthogonal direction V1. Thereafter, the sheet S is spaced from the curved guide wall 72, and extends further from the linear guide wall 71 as it goes downstream in the sheet conveying direction Vs from the front end of the guide 51. Thereafter, the sheet is spaced from the curved guide wall 72, and extends so as to approach the downstream side of the sheet conveying direction Vs toward the forming portion of the conveying path 31, and reaches the nip portion 64 of the conveying roller pair 61, 62.

In this way, the first surface F1 of the front end portion of the guide 51 is brought into contact with the first regulating projection 56 (see fig. 2), and a space 75 through which the sheet S can pass is formed between the first surface F1 of the front end portion of the guide 51 and the linear guide wall 71. A deflection space of the sheet S sufficient for inclination correction of the sheet S is not ensured near the nip 44, and a deflection space 73 of the sheet S is ensured at a position on the downstream side of the leading end of the guide 51. When the sheet conveying operation is performed after the alignment operation is completed, the guide 51 is caused to protrude toward the linear guide wall 71, and the guide 51 is caused to spread the sheet S that is about to enter the nip 44. Therefore, the undulation of the sheet S is eliminated in the vicinity of the nip 44, so that the sheet S is conveyed in a state of being held on the first surface F1 of the guide 51. As a result, the sheet S does not undulate when passing through the nip 44, and sheet damage such as wrinkles and creases is less likely to occur on the sheet S.

According to the embodiment, the sheet conveying apparatus 30 has the registration mechanism 40 and the conveying width variable mechanism 50. The alignment mechanism 40 collates the positions of the leading ends of the sheets by touching the sheets conveyed along the conveying path 31 to the nip 44. The conveying width variable mechanism 50 is provided at a position upstream of the nip 44 in the sheet conveying direction Vs. The conveying width variable mechanism 50 makes the conveying width near the nip portion when the sheet touches the nip portion 44 larger than the conveying width near the nip portion when the sheet passes through the nip portion 44 after the sheet touches the nip portion 44. The following effects are achieved by the above configuration. When the sheet touches the nip 44, a deflection space 74 of the sheet sufficient for inclination correction of the sheet can be secured in the nip 44. Therefore, the sheet is brought into contact with the nip 44, whereby the sheet can be sufficiently deflected to adjust the position of the leading end of the sheet. On the other hand, when the sheet is passed through the nip 44, the guide 51 functions to spread the sheet S that is about to enter the nip 44. Therefore, the undulation of the sheet can be eliminated in the vicinity of the nip portion 44, and the sheet can pass through the nip portion 44 in a state without undulation. Therefore, sheet damage such as wrinkling and creasing can be suppressed from occurring on the sheet.

The alignment mechanism 40 includes a first alignment roller 41 as a driving roller. The first registration roller 41 rotates reversely when the sheet contacts the nip 44. The first registration roller 41 rotates forward when the sheet passes through the nip 44. The following effects are achieved by the above configuration. By using a simple structure of the reverse rotation and the forward rotation of the first registration roller 41, occurrence of sheet damage such as wrinkles and creases on the sheet can be suppressed.

The conveyance width variable mechanism 50 includes a guide 51 that operates in association with the rotation of the first registration roller 41. The guide 51 makes the conveying width near the nip portion when the first registration roller 41 rotates reversely larger than the conveying width near the nip portion when the first registration roller 41 rotates forwardly. The following effects are achieved by the above configuration. The device structure can be simplified as compared with a case where the guide 51 is independently operated separately from the rotation of the first registration roller 41.

In addition, the guide 51 swings coaxially with the first registration roller 41, thereby achieving the following effects. The device structure can be simplified as compared with the case where the guide 51 is swung about a different axis from the first registration roller 41.

The guide 51 is formed longer than the sheet in the first conveyance orthogonal direction V1, thereby achieving the following effects. In comparison with the case where the guide 51 is formed so as to be less than or equal to the length of the sheet along the first conveyance orthogonal direction V1, even in the case of obliquely conveying the sheet, it is easy to hold the sheet entirely over the sheet in the first conveyance orthogonal direction V1 by the guide 51. Therefore, the undulation of the sheet can be more effectively eliminated, and the occurrence of sheet damage such as wrinkles, creases, and the like on the sheet can be more effectively suppressed.

The conveyance width variable mechanism 50 has the following effects by providing the position regulating portions 52 and 53 that regulate the position of the guide 51 when the first registration roller 41 rotates forward and backward. The conveying width near the nip portion can be set to a specific width when the sheet contacts the nip portion 44 and when the sheet passes through the nip portion 44, respectively. That is, the difference in conveying width between the sheet contacting the nip 44 and the sheet passing the nip 44 is less likely to deviate. Therefore, the deviation of the correction degree of the sheet undulation can be suppressed, and the occurrence of sheet damage such as wrinkles and creases on the sheet can be more effectively suppressed.

The position regulating portions 52, 53 include a first stopper 52 and a second stopper 53. The first stopper 52 can abut against the first end of the guide 51 in the first conveyance orthogonal direction V1. The second stopper 53 can abut against the second end of the guide 51 in the first conveyance orthogonal direction V1. The following effects are achieved by the above configuration. The guide 51 can be stably held by the first stopper 52 and the second stopper 53, respectively, as compared with the case where the position regulating portions 52 and 53 include stoppers that can only abut against one end of the guide 51 in the first conveyance orthogonal direction V1. That is, in the first conveyance orthogonal direction V1, the difference in the conveyance width in the vicinity of the nip is less likely to deviate. Therefore, the deviation of the correction degree of the sheet undulation can be suppressed, and the occurrence of sheet damage such as wrinkles and creases on the sheet can be more effectively suppressed.

The sheet conveying apparatus 30 further includes a first conveying roller 61 provided at a position upstream of the registration mechanism 40 in the sheet conveying direction Vs. The first conveying rollers 61 convey the sheet when the sheet passes through the nip portion 44 and the sheet touches the nip portion 44, respectively. The following effects are achieved by the above configuration. By a simple structure using the rotation of the first conveying roller 61, occurrence of sheet damage such as wrinkles and creases on the sheet can be suppressed.

The conveyance path 31 is provided along the vertical surface, thereby achieving the following effects. In the sheet conveying apparatus 30 having the conveying path 31 along the vertical surface, occurrence of sheet damage such as wrinkles and creases on the sheet can be suppressed.

Next, a modification will be described.

The conveyance path 31 is not limited to the case of being provided along a vertical plane.

Fig. 8 is a schematic diagram showing a main portion of the sheet conveying apparatus 130 according to a modification of the embodiment.

As shown in fig. 8, the conveyance path 131 may be provided along a horizontal plane. The conveyance width variable mechanism 150 may include a guide 151 provided above the conveyance path 131. The conveyance width variable mechanism 150 may include a support shaft 159 that supports the guide 151 so as to be swingable. The guide 151 may swing around a support shaft 159 of a different shaft from the first registration roller 41 (first registration shaft 45) as a center.

According to the present modification, when the sheet touches the nip portion 44, the guide 151 is lifted by the deflected sheet S (solid line). Therefore, the sheet S can be sufficiently deflected near the nip 44 to sort the position of the leading end of the sheet S. On the other hand, when the sheet passes through the nip 44, the guide 151 presses the sheet S from above (broken line) by gravity (dead weight). Therefore, the undulation of the sheet can be eliminated in the vicinity of the nip 44, so that the sheet S can pass through the nip 44 in a state without undulation. Therefore, sheet damage such as wrinkling and creasing can be suppressed from occurring on the sheet S.

Next, another modification of the embodiment will be described.

The sheet conveying apparatus 30 is not limited to the case of being disposed between the paper feed portion 14 and the printing portion 13. For example, the sheet conveying device 30 may be disposed near the sheet reversing position. The sheet conveying apparatus 30 may be provided on any one of conveying paths in an image forming system (image forming apparatus, post-processing apparatus).

The guide 51 is not limited to the operation in association with the rotation of the first registration roller 41. For example, the guide 51 may be independently operated separately from the rotation of the first registration roller 41. For example, the sheet conveying apparatus 30 may further include a control unit that controls the operation of the guide 51.

The guide 51 is not limited to swing. The guide 51 can also move forward and backward. For example, the guide 51 may be operated so that the conveying width near the nip portion when the first registration roller 41 rotates in the reverse direction is larger than the conveying width near the nip portion when the first registration roller 41 rotates in the forward direction.

The first registration roller 41 is not limited to the case of performing reverse rotation when the sheet contacts the nip portion 44. For example, the first registration roller 41 may be stopped when the sheet contacts the nip 44. For example, the first registration roller 41 may be reversely rotated after the sheet passes through the nip 44. For example, the sheet conveying apparatus 30 may include a control unit that controls the rotation of the first registration roller 41.

The alignment mechanism 40 is not limited to the case of having the alignment roller pairs 41 and 42. For example, the alignment mechanism 40 may include an alignment roller and a spacer (roller contact member). For example, the alignment mechanism 40 may include at least one rotating body.

The conveying mechanism 60 is not limited to the case of having the conveying roller pairs 61, 62. For example, the conveying mechanism 60 may include a conveying roller and a pad (roller contact member). For example, the conveying mechanism 60 may include at least one rotating body.

The guide 51 is not limited to the case of being longer than the sheet in the first conveyance orthogonal direction V1. For example, the guide 51 may have a length equal to or less than the length of the sheet in the first conveyance orthogonal direction V1. For example, a plurality of guides 51 may be arranged at intervals in the first conveyance orthogonal direction V1. For example, a plate extending in the first conveyance orthogonal direction V1 is provided with a plurality of ribs as guides 51 at intervals in the extending direction of the plate. The number and positions of the guides 51 may be changed according to the specification.

The registration roller is not limited to one. More than two alignment rollers may be provided. The number and positions of the alignment rollers may be changed according to the specification.

The conveying rollers are not limited to two. One or more than three conveying rollers may be provided. The number and positions of the conveying rollers may be changed according to the specification.

According to at least one embodiment described above, the sheet conveying apparatus 30 has the aligning mechanism 40 and the conveying width variable mechanism 50. The alignment mechanism 40 collates the positions of the leading ends of the sheets by touching the sheets conveyed along the conveying path 31 to the nip 44. The conveying width variable mechanism 50 is provided at a position upstream of the nip 44 in the sheet conveying direction Vs. The conveying width variable mechanism 50 makes the conveying width near the nip portion when the sheet touches the nip portion 44 larger than the conveying width near the nip portion when the sheet passes through the nip portion 44 after the sheet touches the nip portion 44. The following effects are achieved by the above configuration. When the sheet touches the nip 44, a deflection space 74 of the sheet sufficient for inclination correction of the sheet can be secured near the nip 44. Therefore, the sheet is brought into contact with the nip 44, whereby the sheet can be sufficiently deflected to adjust the position of the leading end of the sheet. On the other hand, when the sheet is passed through the nip 44, the guide 51 functions to spread the sheet S that is about to enter the nip 44. Therefore, the undulation of the sheet can be eliminated in the vicinity of the nip portion 44, so that the sheet can pass through the nip portion 44 in a state without undulation. Therefore, sheet damage such as wrinkling and creasing can be suppressed from occurring on the sheet.

While several embodiments are illustrated, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other modes, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The present invention is not limited to the above embodiments and modifications, and is intended to be included in the scope and spirit of the present invention.

Claims

1. A sheet conveying apparatus is characterized by comprising:

an aligning mechanism that rotates forward or stops rotating in a conveying direction of a sheet or rotates reversely in a direction opposite to the direction of the forward rotation, the aligning mechanism collating a position of a leading end of the sheet conveyed along a conveying path by touching the sheet to a nip; and

a conveying width variable mechanism that is provided at an upstream position of the nip portion in a conveying direction of the sheet and that makes a width of the conveying path in a vicinity of the nip portion, that is, a first position, when the sheet touches the nip portion larger than a width of the conveying path in a vicinity of the nip portion, that is, a second position, when the sheet passes the nip portion after the sheet touches the nip portion,

the alignment mechanism includes a driving roller that rotates in a reverse direction when the sheet contacts the nip portion and rotates in a forward direction when the sheet passes through the nip portion,

the conveying width variable mechanism includes a guide that operates in conjunction with rotation of the driving roller and makes the width of the conveying path at the first position when the driving roller rotates in the reverse direction larger than the width of the conveying path at the second position when the driving roller rotates in the forward direction,

the conveying width variable mechanism further includes a position restricting portion that restricts a position of the guide when the drive roller rotates in a forward direction and when the drive roller rotates in a reverse direction,

the guide is located at a first position when the alignment mechanism stops rotating or rotates reversely to sort sheets, is located at a second position when the alignment mechanism rotates forwardly to convey sheets,

the guide moves to the second position in accordance with the forward rotation of the driving roller, and when a direction orthogonal to the sheet conveyance direction in the sheet plane of the sheet is a first conveyance orthogonal direction and a direction orthogonal to the sheet conveyance direction and the first conveyance orthogonal direction is a second conveyance orthogonal direction,

the position regulating portion includes a first stopper capable of abutting against a first end portion of the guide in the first conveyance orthogonal direction, and a second stopper capable of abutting against a second end portion of the guide in the first conveyance orthogonal direction,

the first stopper and the second stopper each include a first restricting protrusion, a second restricting protrusion, and a connecting portion that connects the first restricting protrusion and the second restricting protrusion,

the first restricting projection may be abutted against a surface of the leading end portion of the guide on the side of the conveying path, the second restricting projection may be abutted against a surface of the leading end portion of the guide on the side opposite to the conveying path,

the torque transmission cutting portion cuts off torque transmission when the tip end portion of the guide abuts against the first regulating projection in a case where the driving roller rotates in the forward direction; when the drive roller rotates in the reverse direction, the torque transmission cut-off portion cuts off torque transmission when the tip end portion of the guide abuts on the second regulating projection.

2. The sheet conveying apparatus according to claim 1, wherein,

the guide is formed longer than the sheet in a direction orthogonal to the first conveyance direction.

3. The sheet conveying apparatus according to claim 1 or 2, wherein,

the sheet conveying apparatus further includes:

and conveying rollers provided at positions upstream of the alignment mechanism in the conveying direction of the sheet, the conveying rollers conveying the sheet, respectively, when the sheet is passed through the nip portion and when the sheet is brought into contact with the nip portion.

4. The sheet conveying apparatus according to claim 1 or 2, wherein,

the conveying path is arranged along a vertical plane.

5. The sheet conveying apparatus according to claim 1 or 2, wherein,

the conveying path is arranged along a horizontal plane, the guide is arranged above the conveying path,

the transport width variable mechanism includes: and a support shaft for supporting the guide to swing freely.

6. An image forming system for forming an image on a sheet, characterized in that,

the image forming system includes the sheet conveying apparatus according to any one of claims 1 to 5.